The earliest type of printing to occur in Europe was woodblock prints. Blocks were used to print on fabrics, and also to make ephemeral objects like playing cards. Despite the early use of block printing, there is only shakey evidence that books were printed by means of blocks prior to the invention of the printing press.
The earliest ‘block books’ - sometimes called 'Pauper's bibles (biblia pauperum) - were heavily illustrated abridged versions of the bible (see one here). These block books were most popular in the 1460s, but they gradually fell out of popularity. Despite the decline of block books, wood blocks remained important to European printing. Illustrations, intitials, and type ornaments were all printed using wood blocks until the end of the age of the printing press.
For scholarship on the history of European wood block (xylographic illustration) see:
This introductory essay from the MET museum
![Opera noua contemplatiua p[er] ogni fidel christiano laquale tratta de le figure del testamento vecchio, Andrea Vavassori (1530)](https://hob.gseis.ucla.edu/Spotlights/Esquivel_2.jpg)
For printed introductions see:
Hind, A. M. (1935). An introduction to a history of woodcut: 2. London: Constable.
Parshall, P. W., Schoch, R., Areford, D. S., Field, R. S., & Schmidt, P. (2005). Origins of European printmaking: Fifteenth-century woodcuts and their public. Washington, D.C: National Gallery of Art.